1. Field of the Invention
The present invention relates, in general, to an axial flow fan for refrigerators, used for cooling the machines set within the machine compartment of a refrigerator, and, more particularly, to an axial flow fan for refrigerators, designed to have three blades, a diameter ratio of 0.21 to 0.25, a large sweep angle, a large pitch angle and a high camber ratio, thus forming a smooth air circulation within the machine compartment and more effectively cooling the machines within the machine compartment.
2. Description of the Prior Art
FIG. 1 is a perspective view showing the construction of a conventional side-by-side type refrigerator. FIG. 2 is a perspective view, showing the interior construction of the conventional side-by-side type refrigerator, and a cool air current within the refrigerator. FIG. 3 is a left-side view of FIG. 2. FIG. 4 is a right-side view of FIG. 2. FIG. 5 is a plan view, showing the interior construction of the machine compartment of a conventional refrigerator and a cool air current within the compartment. FIG. 6 is a front view of FIG. 2.
As shown in FIGS. 1 to 4, the cabinet of a conventional side-by-side type refrigerator is vertically partitioned into two vertical sections in its interior, thus defining a freezer compartment 10 within one of the two vertical sections and a fresh compartment 20 within the other vertical section.
In the above refrigerator, an evaporator 11 is installed in the rear portion of the freezer compartment 10 and generates cool air through a heat exchanging process. A cool air supply fan 13 is installed above the evaporator 11 and provides suction for drawing the cool air from the evaporator 11 and supplying the cool air into both the freezer compartment 10, and the fresh compartment 20.
In the lower section of the cabinet of the above refrigerator at a position under the two compartments 10 and 20, is an equipment compartment 21, in which a variety of equipment, such as a compressor 22, a condenser 23 and an axial flow fan 25, are located. As well known to those skilled in the art, the compressor 22 is used for compressing refrigerant for the refrigeration cycle, the condenser 23 condenses the compressed refrigerant from the compressor 22 through a heat exchanging process, and the axial flow fan 25 is used for cooling both the compressor 22 and the condenser 23 using an air current.
The above axial flow fan 25 is firmly mounted to the rotating shaft of a drive motor 26, and is rotated in conjunction with the motor 26. A shroud 27 is installed around the blades of the axial flow fan 25 to protect the blades.
In an operation of such a conventional side-by-side type refrigerator, refrigerant is compressed by the compressor 22 to become high temperature and high pressure gas refrigerant, and flows into the condenser 23. In the condenser 23, the gas refrigerant dissipates heat into the surrounding air and becomes liquid refrigerant acquiring the room temperature, and a high pressure.
The liquid refrigerant is, thereafter, output from the condenser 23 to pass through a capillary tube while being reduced in pressure, thus partially becoming two-phased refrigerant including a liquid phase and a gas phase. The refrigerant flows from the capillary tube into the evaporator 11 within the freezer compartment 10 and is completely vaporized within the evaporator 11 to become low pressure gas refrigerant while receiving heat from air surrounding the evaporator 11, thus cooling the air.
The cool air, formed through a heat exchanging process of the evaporator 11, is supplied into both the freezer compartment 10 and the fresh compartment 20. The above-mentioned refrigeration cycle is repeated to keep the two compartments 10 and 20 at desired low temperatures.
During such an operation of the refrigerator, the axial flow fan 25 installed in the machine compartment 21 cools both the compressor 22 and the condenser 23 using an air current.
The air current from the axial flow fan 25 flows within the machine compartment 21 as follows: Outside air, or atmospheric air is primarily introduced into the machine compartment 21 through an air inlet port 21 due to the suction force provided by the axial flow fan 25.
Within the machine compartment 21, the inlet air passes through the drive motor 26 by the suction force of the fan 25, and passes through both the fan 25 and the shroud 27 so as to reach the condenser 23.
The air passes, through the condenser 23 while absorbing heat dissipated from the refrigerant flowing within the condenser 23. Thus, the air cools the condenser 23.
After passing through the condenser 23, the air passes through the compressor 22, cooling the surface of the compressor""s housing, prior to being discharged from the machine compartment 21 into the atmosphere through an air outlet port 21.
In a brief description, inlet air, sucked into the machine compartment 21 by the suction force of the axial flow fan 25, primarily cools the condenser 23, thus improving heat exchange efficiency of the condenser 23 and finally improving refrigeration efficiency of the refrigerator. The inlet air within the machine compartment 21 secondarily cools the external surface of the compressor 22, thus keeping the compressor 22 at a desired low temperature, and preventing deterioration of the operational performance of the compressor.
Therefore, the operational performance of the axial flow fan is one of the important factors determining the refrigeration efficiency, and the operational noise of the refrigerator.
Such a conventional axial flow fan 25 for refrigerators typically has three blades, an outer diameter of the fan 25 ranging from 145 mm to 165 mm, a small blade sweep angle, a small blade pitch angle, and a low blade camber ratio, causing a refrigerator to have low refrigeration efficiency, and to generate noise substantial enough to disturb individuals near the refrigerator.
A small blade sweep angle increases the undesirable operational noise of the fan 25. A small blade pitch results in a reduction in the width of the blades, therefore an axial flow fan such as fan 25 is not suitable to draw a desirable quantity of air. When the blade camber ratio (%) is as low as described above, it is almost impossible to effectively increase the static pressure of fluid passing through both the axial flow fan and the shroud. In order to overcome such a problem, the fan 25 has to be rotated at an exceedingly high rpm.
Therefore, it is necessary to optimally design a variety of blade designing factors, such as the number of blades, diameter ratio, sweep angle, pitch angle and camber ratio so as to allow the designing factors to agree with desired operational conditions of a refrigerator. When such designing factors of the axial flow fan are optimally designed as described above, it is possible to optimally operate the axial flow fan through an inverter control process while supplying a adequate quantity of air to both the compressor and the condenser and achieving an adequate rpm of the fan, and effectively reducing operational noise of the fan.
Accordingly, the present axial flow fan was invented having in mind the above problems occurring in the prior art, and an object of the present invention is to provide an axial flow fan for refrigerators, which is designed to allow air to actively circulate within the machine compartment of a refrigerator, thus accomplishing smooth inflow and outflow of air, and eliminating operational noise caused by disturbed air circulation within the machine compartment and increasing the quantity of inflow and outflow air, and delivering an adequate quantity of air to both the compressor and the condenser, and effectively reducing operational noise of the refrigerator.
In order to accomplish the above object, the preferred embodiment of the present invention provides an axial flow fan for refrigerators, comprising a hub mounted to the rotating shaft of a motor, with a plurality of blades regularly fixed around the hub. In the axial flow fan of this invention, a variety of blade designing factors, such as the number of blades, diameter ratio, sweep angle, pitch angle and camber ratio are optimally designed to allow the designing factors to agree with desired operational conditions of a refrigerator. This axial flow fan thus supplies an adequate quantity of air to both the compressor and the condenser within the machine compartment, while effectively reducing operational noise of the refrigerator.